[fwd] / fw.c

/* -*-c-*-
 *
 * $Id: fw.c,v 1.3 1999/07/26 23:30:42 mdw Exp $
 *
 * Port forwarding thingy
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the `fw' port forwarder.
 *
 * `fw' is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * `fw' is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with `fw'; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: fw.c,v $
 * Revision 1.3  1999/07/26 23:30:42  mdw
 * Major reconstruction work for new design.
 *
 * Revision 1.2  1999/07/03 13:55:17  mdw
 * Various changes.  Add configuration grammar to help text.  Change to
 * root directory and open syslog when forking into background.
 *
 * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
 * Initial revision.
 *
 */

/*----- Header files ------------------------------------------------------*/

#include "config.h"

#include <ctype.h>
#include <errno.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <unistd.h>
#include <syslog.h>

#include <mLib/dstr.h>
#include <mLib/mdwopt.h>
#include <mLib/quis.h>
#include <mLib/report.h>
#include <mLib/sel.h>
#include <mLib/sig.h>
#include <mLib/sub.h>

#include "bres.h"
#include "conf.h"
#include "endpt.h"
#include "exec.h"
#include "fattr.h"
#include "fw.h"
#include "scan.h"
#include "source.h"

/*----- Global variables --------------------------------------------------*/

sel_state *sel;				/* Multiplexor for nonblocking I/O */

/*----- Static variables --------------------------------------------------*/

static unsigned flags = 0;		/* Global state flags */
static unsigned active = 0;		/* Number of active things */

#define FW_SYSLOG 1u
#define FW_QUIET 2u
#define FW_SET 4u

/*----- Main code ---------------------------------------------------------*/

/* --- @fw_log@ --- *
 *
 * Arguments:	@time_t t@ = when the connection occurred or (@-1@)
 *		@const char *fmt@ = format string to fill in
 *		@...@ = other arguments
 *
 * Returns:	---
 *
 * Use:		Logs a connection.
 */

void fw_log(time_t t, const char *fmt, ...)
{
  struct tm *tm;
  dstr d = DSTR_INIT;
  va_list ap;

  if (flags & FW_QUIET)
    return;

  if (t == -1)
    t = time(0);
  tm = localtime(&t);
  DENSURE(&d, 64);
  d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S", tm);
  DPUTC(&d, ' ');
  va_start(ap, fmt);
  dstr_vputf(&d, fmt, ap);
  va_end(ap);
  if (flags & FW_SYSLOG)
    syslog(LOG_NOTICE, "%s", d.buf);
  else {
    DPUTC(&d, '\n');
    dstr_write(&d, stderr);
  }
  DDESTROY(&d);
}

/* --- @fw_inc@, @fw_dec@ --- *
 *
 * Arguments:	---
 *
 * Returns:	---
 *
 * Use:		Increments or decrements the active thing count.  `fw' won't
 *		quit while there are active things.
 */

void fw_inc(void) { flags |= FW_SET; active++; }
void fw_dec(void) { if (active) active--; }

/* --- @fw_exit@ --- *
 *
 * Arguments:	---
 *
 * Returns:	---
 *
 * Use:		Exits when appropriate.
 */

static void fw_exit(void)
{
  endpt_killall();
  source_killall();
}

/* --- @fw_tidy@ --- *
 *
 * Arguments:	@int n@ = signal number
 *		@void *p@ = an uninteresting argument
 *
 * Returns:	---
 *
 * Use:		Handles various signals and causes a clean tidy-up.
 */

static void fw_tidy(int n, void *p)
{
  const char *sn = "unexpected signal (bug!)";
  if (n == SIGTERM)
    sn = "SIGTERM";
  else if (n == SIGINT)
    sn = "SIGINT";

  fw_log(-1, "closing down on %s", sn);
  fw_exit();
}

/* --- Standard GNU help options --- */

static void version(FILE *fp)
{
  fprintf(fp, "%s version " VERSION "\n", QUIS);
}

static void usage(FILE *fp)
{
  fprintf(stderr, "Usage: %s [-db] [-f file] [config statements...]\n",
	  QUIS);
}

static void help(FILE *fp)
{
  version(fp);
  fputc('\n', fp);
  usage(fp);
  fputs("\n\
An excessively full-featured port-forwarder, which subsumes large chunks\n\
of the functionality of inetd, netcat, and normal cat.  Options available\n\
are:\n\
\n\
-h, --help		Display this help message.\n\
-v, --version		Display the program's version number.\n\
-u, --usage		Display a terse usage summary.\n\
\n\
-f, --file=FILE		Read configuration from a file.\n\
-d, --daemon		Fork into background after initializing.\n\
\n\
Configuration may be supplied in one or more configuration files, or on\n\
the command line (or both).  If no `-f' option is present, and no\n\
configuration is given on the command line, the standard input stream is\n\
read.\n\
\n\
Configuration is free-form.  Comments begin with a `#' character and\n\
continue to the end of the line.  Each command line argument is considered\n\
to be a separate line.\n\
\n\
The syntax is too complicated to describe here.  Read the manual.\n\
", fp);
}

/* --- @main@ --- *
 *
 * Arguments:	@int argc@ = number of command line arguments
 *		@char *argv[]@ = vector of argument strings
 *
 * Returns:	---
 *
 * Use:		Simple port-forwarding server.
 */

int main(int argc, char *argv[])
{
  unsigned f = 0;
  sel_state sst;
  sig s_term, s_int;
  scanner sc;

  enum {
    f_bogus = 1,
    f_file = 2,
    f_fork = 8
  };

  /* --- Initialize things --- */

  ego(argv[0]);
  sel = &sst;
  sel_init(sel);
  sub_init();
  sig_init(sel);
  bres_init(sel);
  exec_init();
  fattr_init(&fattr_global);
  scan_create(&sc);

  /* --- Set up some signal handlers --- */

  sig_add(&s_term, SIGTERM, fw_tidy, 0);
  sig_add(&s_int, SIGINT, fw_tidy, 0);
  atexit(fw_exit);

  /* --- Parse command line options --- */

  for (;;) {
    static struct option opts[] = {

      /* --- Standard GNU help options --- */

      { "help", 	0,		0,	'h' },
      { "version",	0,		0,	'v' },
      { "usage",	0,		0,	'u' },

      /* --- Other useful arguments --- */

      { "file",		OPTF_ARGREQ,	0,	'f' },
      { "fork",		0,		0,	'd' },
      { "daemon",	0,		0,	'd' },
      { "quiet",	0,		0,	'q' },

      /* --- Magic terminator --- */

      { 0,		0,		0,	0 }
    };
    int i = mdwopt(argc, argv, "+hvu f:d", opts, 0, 0, 0);

    if (i < 0)
      break;
    switch (i) {
      case 'h':
	help(stdout);
	exit(0);
	break;
      case 'v':
	version(stdout);
	exit(0);
	break;
      case 'u':
	usage(stdout);
	exit(0);
	break;
      case 'f':
	if (strcmp(optarg, "-") == 0)
	  scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
	else {
	  FILE *fp;
	  if ((fp = fopen(optarg, "r")) == 0)
	    die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
	  scan_add(&sc, scan_file(fp, optarg, 0));
	}
	f |= f_file;
	break;
      case 'd':
	f |= f_fork;
	break;
      case 'q':
	flags |= FW_QUIET;
	break;
      default:
	f |= f_bogus;
	break;
    }
  }

  if (f & f_bogus) {
    usage(stderr);
    exit(1);
  }

  /* --- Deal with the remaining arguments --- */

  if (optind < argc)
    scan_add(&sc, scan_argv(argv + optind));
  else if (f & f_file)
    /* Cool */;
  else if (!isatty(STDIN_FILENO))
    scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
  else {
    moan("no configuration given and stdin is a terminal.");
    moan("type `%s --help' for usage information.", QUIS);
    exit(1);
  }

  /* --- Parse the configuration now gathered --- */

  conf_parse(&sc);

  /* --- Fork into the background --- */

  if (f & f_fork) {
    pid_t kid;

    kid = fork();
    if (kid == -1)
      die(1, "couldn't fork: %s", strerror(errno));
    if (kid != 0)
      _exit(0);

    close(0); close(1); close(2);
    chdir("/");
    setsid();

    kid = fork();
    if (kid != 0)
      _exit(0);

    flags |= FW_SYSLOG;
    openlog(QUIS, 0, LOG_DAEMON);
  }

  /* --- Let rip --- */

  if (!(flags & FW_SET))
    moan("nothing to do!");
  signal(SIGPIPE, SIG_IGN);
  while (active)
    sel_select(sel);
  return (0);
}

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
e82f7154	1	/* --c--
e82f7154	2	*
61e3dbdf	3	* $Id: fw.c,v 1.3 1999/07/26 23:30:42 mdw Exp $
e82f7154	4	*
	5	* Port forwarding thingy
	6	*
61e3dbdf	7	* (c) 1999 Straylight/Edgeware
e82f7154	8	*/
	9
	10	/----- Licensing notice --------------------------------------------------
	11	*
	12	* This file is part of the `fw' port forwarder.
	13	*
	14	* `fw' is free software; you can redistribute it and/or modify
	15	* it under the terms of the GNU General Public License as published by
	16	* the Free Software Foundation; either version 2 of the License, or
	17	* (at your option) any later version.
	18	*
	19	* `fw' is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	22	* GNU General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU General Public License
	25	* along with `fw'; if not, write to the Free Software Foundation,
	26	* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	27	*/
	28
	29	/----- Revision history --------------------------------------------------
	30	*
	31	* $Log: fw.c,v $
61e3dbdf	32	* Revision 1.3 1999/07/26 23:30:42 mdw
	33	* Major reconstruction work for new design.
	34	*
afd7451e	35	* Revision 1.2 1999/07/03 13:55:17 mdw
	36	* Various changes. Add configuration grammar to help text. Change to
	37	* root directory and open syslog when forking into background.
	38	*
	39	* Revision 1.1.1.1 1999/07/01 08:56:23 mdw
	40	* Initial revision.
e82f7154	41	*
	42	*/
	43
	44	/----- Header files ------------------------------------------------------/
	45
	46	#include "config.h"
	47
	48	#include <ctype.h>
	49	#include <errno.h>
61e3dbdf	50	#include <signal.h>
61e3dbdf	51	#include <stdarg.h>
e82f7154	52	#include <stdio.h>
	53	#include <stdlib.h>
	54	#include <string.h>
61e3dbdf	55	#include <time.h>
e82f7154	56
	57	#include <unistd.h>
	58	#include <syslog.h>
	59
61e3dbdf	60	#include <mLib/dstr.h>
e82f7154	61	#include <mLib/mdwopt.h>
	62	#include <mLib/quis.h>
	63	#include <mLib/report.h>
	64	#include <mLib/sel.h>
61e3dbdf	65	#include <mLib/sig.h>
e82f7154	66	#include <mLib/sub.h>
e82f7154	67
e82f7154	68	#include "bres.h"
e82f7154	69	#include "conf.h"
61e3dbdf	70	#include "endpt.h"
	71	#include "exec.h"
	72	#include "fattr.h"
afd7451e	73	#include "fw.h"
e82f7154	74	#include "scan.h"
61e3dbdf	75	#include "source.h"
e82f7154	76
afd7451e	77	/----- Global variables --------------------------------------------------/
e82f7154	78
e82f7154	79	sel_state sel; / Multiplexor for nonblocking I/O */
61e3dbdf	80
	81	/----- Static variables --------------------------------------------------/
	82
	83	static unsigned flags = 0; /* Global state flags */
	84	static unsigned active = 0; /* Number of active things */
	85
	86	#define FW_SYSLOG 1u
	87	#define FW_QUIET 2u
	88	#define FW_SET 4u
e82f7154	89
	90	/----- Main code ---------------------------------------------------------/
	91
61e3dbdf	92	/* --- @fw_log@ --- *
	93	*
	94	* Arguments: @time_t t@ = when the connection occurred or (@-1@)
	95	* @const char *fmt@ = format string to fill in
	96	* @...@ = other arguments
	97	*
	98	* Returns: ---
	99	*
	100	* Use: Logs a connection.
	101	*/
	102
	103	void fw_log(time_t t, const char *fmt, ...)
	104	{
	105	struct tm *tm;
	106	dstr d = DSTR_INIT;
	107	va_list ap;
	108
	109	if (flags & FW_QUIET)
	110	return;
	111
	112	if (t == -1)
	113	t = time(0);
	114	tm = localtime(&t);
	115	DENSURE(&d, 64);
	116	d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S", tm);
	117	DPUTC(&d, ' ');
	118	va_start(ap, fmt);
	119	dstr_vputf(&d, fmt, ap);
	120	va_end(ap);
	121	if (flags & FW_SYSLOG)
	122	syslog(LOG_NOTICE, "%s", d.buf);
	123	else {
	124	DPUTC(&d, '\n');
	125	dstr_write(&d, stderr);
	126	}
	127	DDESTROY(&d);
	128	}
	129
	130	/* --- @fw_inc@, @fw_dec@ --- *
	131	*
	132	* Arguments: ---
	133	*
	134	* Returns: ---
	135	*
	136	* Use: Increments or decrements the active thing count. `fw' won't
	137	* quit while there are active things.
	138	*/
	139
	140	void fw_inc(void) { flags \|= FW_SET; active++; }
	141	void fw_dec(void) { if (active) active--; }
	142
	143	/* --- @fw_exit@ --- *
	144	*
	145	* Arguments: ---
	146	*
	147	* Returns: ---
	148	*
	149	* Use: Exits when appropriate.
	150	*/
	151
	152	static void fw_exit(void)
	153	{
	154	endpt_killall();
	155	source_killall();
156	}
157
158	/* --- @fw_tidy@ --- *
159	*
160	* Arguments: @int n@ = signal number
161	* @void *p@ = an uninteresting argument
162	*
163	* Returns: ---
164	*
165	* Use: Handles various signals and causes a clean tidy-up.
166	*/
167
168	static void fw_tidy(int n, void *p)
169	{
170	const char *sn = "unexpected signal (bug!)";
171	if (n == SIGTERM)
172	sn = "SIGTERM";
173	else if (n == SIGINT)
174	sn = "SIGINT";
175
176	fw_log(-1, "closing down on %s", sn);
177	fw_exit();
178	}
179
e82f7154	180	/* --- Standard GNU help options --- */
	181
	182	static void version(FILE *fp)
	183	{
	184	fprintf(fp, "%s version " VERSION "\n", QUIS);
	185	}
	186
	187	static void usage(FILE *fp)
	188	{
afd7451e	189	fprintf(stderr, "Usage: %s [-db] [-f file] [config statements...]\n",
e82f7154	190	QUIS);
	191	}
	192
	193	static void help(FILE *fp)
	194	{
	195	version(fp);
	196	fputc('\n', fp);
	197	usage(fp);
	198	fputs("\n\
61e3dbdf	199	An excessively full-featured port-forwarder, which subsumes large chunks\n\
	200	of the functionality of inetd, netcat, and normal cat. Options available\n\
	201	are:\n\
e82f7154	202	\n\
	203	-h, --help Display this help message.\n\
	204	-v, --version Display the program's version number.\n\
	205	-u, --usage Display a terse usage summary.\n\
	206	\n\
	207	-f, --file=FILE Read configuration from a file.\n\
61e3dbdf	208	-d, --daemon Fork into background after initializing.\n\
e82f7154	209	\n\
	210	Configuration may be supplied in one or more configuration files, or on\n\
	211	the command line (or both). If no `-f' option is present, and no\n\
	212	configuration is given on the command line, the standard input stream is\n\
	213	read.\n\
	214	\n\
	215	Configuration is free-form. Comments begin with a `#' character and\n\
afd7451e	216	continue to the end of the line. Each command line argument is considered\n\
61e3dbdf	217	to be a separate line.\n\
afd7451e	218	\n\
61e3dbdf	219	The syntax is too complicated to describe here. Read the manual.\n\
e82f7154	220	", fp);
	221	}
	222
	223	/* --- @main@ --- *
	224	*
	225	* Arguments: @int argc@ = number of command line arguments
	226	* @char *argv[]@ = vector of argument strings
	227	*
	228	* Returns: ---
	229	*
	230	* Use: Simple port-forwarding server.
	231	*/
	232
	233	int main(int argc, char *argv[])
	234	{
	235	unsigned f = 0;
	236	sel_state sst;
61e3dbdf	237	sig s_term, s_int;
61e3dbdf	238	scanner sc;
e82f7154	239
	240	enum {
	241	f_bogus = 1,
	242	f_file = 2,
e82f7154	243	f_fork = 8
	244	};
	245
	246	/* --- Initialize things --- */
	247
	248	ego(argv[0]);
	249	sel = &sst;
	250	sel_init(sel);
	251	sub_init();
61e3dbdf	252	sig_init(sel);
e82f7154	253	bres_init(sel);
61e3dbdf	254	exec_init();
	255	fattr_init(&fattr_global);
	256	scan_create(&sc);
	257
	258	/* --- Set up some signal handlers --- */
	259
	260	sig_add(&s_term, SIGTERM, fw_tidy, 0);
	261	sig_add(&s_int, SIGINT, fw_tidy, 0);
	262	atexit(fw_exit);
e82f7154	263
	264	/* --- Parse command line options --- */
	265
	266	for (;;) {
	267	static struct option opts[] = {
	268
	269	/* --- Standard GNU help options --- */
	270
	271	{ "help", 0, 0, 'h' },
	272	{ "version", 0, 0, 'v' },
	273	{ "usage", 0, 0, 'u' },
	274
	275	/* --- Other useful arguments --- */
	276
	277	{ "file", OPTF_ARGREQ, 0, 'f' },
61e3dbdf	278	{ "fork", 0, 0, 'd' },
	279	{ "daemon", 0, 0, 'd' },
	280	{ "quiet", 0, 0, 'q' },
e82f7154	281
	282	/* --- Magic terminator --- */
	283
	284	{ 0, 0, 0, 0 }
	285	};
61e3dbdf	286	int i = mdwopt(argc, argv, "+hvu f:d", opts, 0, 0, 0);
e82f7154	287
	288	if (i < 0)
	289	break;
	290	switch (i) {
	291	case 'h':
	292	help(stdout);
	293	exit(0);
	294	break;
	295	case 'v':
	296	version(stdout);
	297	exit(0);
	298	break;
	299	case 'u':
	300	usage(stdout);
	301	exit(0);
	302	break;
61e3dbdf	303	case 'f':
	304	if (strcmp(optarg, "-") == 0)
	305	scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
	306	else {
	307	FILE *fp;
	308	if ((fp = fopen(optarg, "r")) == 0)
	309	die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
	310	scan_add(&sc, scan_file(fp, optarg, 0));
	311	}
e82f7154	312	f \|= f_file;
e82f7154	313	break;
61e3dbdf	314	case 'd':
e82f7154	315	f \|= f_fork;
e82f7154	316	break;
61e3dbdf	317	case 'q':
	318	flags \|= FW_QUIET;
	319	break;
e82f7154	320	default:
	321	f \|= f_bogus;
	322	break;
	323	}
	324	}
	325
	326	if (f & f_bogus) {
	327	usage(stderr);
	328	exit(1);
	329	}
	330
	331	/* --- Deal with the remaining arguments --- */
	332
61e3dbdf	333	if (optind < argc)
	334	scan_add(&sc, scan_argv(argv + optind));
	335	else if (f & f_file)
	336	/* Cool */;
	337	else if (!isatty(STDIN_FILENO))
	338	scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
	339	else {
	340	moan("no configuration given and stdin is a terminal.");
	341	moan("type `%s --help' for usage information.", QUIS);
	342	exit(1);
e82f7154	343	}
e82f7154	344
61e3dbdf	345	/* --- Parse the configuration now gathered --- */
e82f7154	346
61e3dbdf	347	conf_parse(&sc);
e82f7154	348
	349	/* --- Fork into the background --- */
	350
	351	if (f & f_fork) {
	352	pid_t kid;
	353
	354	kid = fork();
	355	if (kid == -1)
	356	die(1, "couldn't fork: %s", strerror(errno));
	357	if (kid != 0)
	358	_exit(0);
	359
	360	close(0); close(1); close(2);
afd7451e	361	chdir("/");
e82f7154	362	setsid();
	363
	364	kid = fork();
	365	if (kid != 0)
	366	_exit(0);
afd7451e	367
	368	flags \|= FW_SYSLOG;
	369	openlog(QUIS, 0, LOG_DAEMON);
e82f7154	370	}
	371
	372	/* --- Let rip --- */
	373
61e3dbdf	374	if (!(flags & FW_SET))
	375	moan("nothing to do!");
	376	signal(SIGPIPE, SIG_IGN);
	377	while (active)
e82f7154	378	sel_select(sel);
	379	return (0);
	380	}
	381
	382	/----- That's all, folks -------------------------------------------------/